Engine-piston.



C. DI 8L P. JGHNSON.

ENGINE FISTON.

APPLICATION FILED IuIIE zo. I9I7.

1,252,269, Patented Jan. 1,1918;

2 SHEETS-:SHEET 2.

INI/ENToRs WITNESSES ATTORNEY 50 l v surface thereof to allow clearance for thel l vherein fully ,ses

CHARLES D. JOHNSON AND PETER C. JOHNSON, OF HALIFAX, NOVA SCOTIA, CANADA.

ENGINE-PISTON.

ion of Canada have invented new and useful Improvements in Engine-Pistons, of which the following is a specification.

This invention relates to engine pistons and the object of the invention is to provide a piston of novel construction which will.

insure a thorough scavenging ofthe burned gases from the combustion chamber and -particularlyfrom the'clearance or compression space of the combustion chamber even after the exhaust stroke of the connecting rod is completed.

With the above and otherobjects in view, the invention consists in the novel construction,'combination and arrangement of parts described, illustratedI an claimed. I

In the accompanying drawings Figure 1 is asectional view taken diametrically of the improved piston and a cylinder in-which the piston is mounted.

Fig. 2 is a detail viewof the piston with the collar and spring removed.

Fig. 3 is a detail v'iewof the collar. Fig. 4 is a detail view of the spring. l

Referring to the drawings 1 designates a cylinder in which'the improved piston is shown as mounted to reciprocate, said cylinder being of the usual formation now commonly employed in internal combustion engines.

The piston consists of two main members or sections, 2 designating what may be termed the outer section and 3 thefinner section, said 'members'or sections 2 and 3 having a telescopic relation to each other as clearly indicated in Fig. 1.

The outer section or member 2 of the piston is provided with the usual packing rings 4 which Operate in contact with the cylinder Wall and said member 2 is of approximate uniform externall diameter throughout. The head of the piston member 2 is formed with a recess 6 in the outer exhaust valve, wherea valve in the head motor 1s employed. The inner' piston mem'- ber B/is practically of uniform diameter.

throughout, the lower portion of said meml ber 3 being externally threaded as Shown Specification of Letters Patent.

'13 c arried by the inner piston member 3 and Agrooved as shown, as is also the opposing each other.

Patented aan. i, iets.

Application filed June 20, 1917. 'Serial No. 175,888.

at 7 to enable a collar 8 to be threaded thereon and finally secured ixedly in position thereon by means of a set screw9 which is inserted through the section or memberfu `60 from inside as shown in Fig. 1. 10 desigA nates the connecting rod for the piston which is attached tothepiston pin 11. This piston piny is carried by the inner section or member 3of the piston.

The outer section 2 of the piston is formed at diametrically opposite places with slots 12 extending longitudinally thereof and therethrough which slots receive guide pins securedvin relation to the latter by means of lock nuts 14. A compression spring 15 surrounds the piston member 3 and is interposed between the collar 8 and the edge 16 of the outer member 2, said spring exerting-its V7.5 tension to hold the piston members 2 and 3 yieldingly and normally in the position shown in Fig. 1. The face 16 against which the spring bears is preferably concaved or face 17 of the collar 8. The concaving or grooving of said faces or shoulders is not essential however as they may be left flat if so desired. The head y18 ofthe inner piston member 3 is formed-with one or more compression relief vents '19 so as not to interfere with the action of the spring 15 or the movement of the heads .5 and 18 of the piston members 2 and 3 respectively toward Assuming for example that the compression of the engine cylinder and piston is seventy pounds per square inch, the collar 8 is adjusted by its threaded connection with thepiston member 3 until it requires a pres- 95 sure of sixty-nine pounds .per square inch to force the pistoii 2 downwardly until the head thereof rests against the head of the piston member 3 or approaches in close proximity thereto. The members 2 and 3 of the piston 10o should provide for a movement of the head' 5 toward the' head 18 sufficient to leave the spring 15 will stand. Therefore the piston 2 is forced downwardly until the head thereof approaches closely to or contacts with the head of the piston member 3. During the explosion/'or combustion stroke, the piston v limit of the stroke of the hollow piston, the

member 2 thereof reaches nearly -to the top of the cylinder 1, thus forcing out all or practically all of the burned gases. This of course greatly increases the power efiiciency of the-engine by insuring a fresh and highly combustibleA charge free from and unimpaired by any burned gases. Another imu portant advantage of the invention resides v in the location of the spring 15 which is far removed from the piston head 5 which is subjected to the greatest heat. The spring is thus protected and is enabled to retain its resilient properties for an indefinite period of time.

We claim 1. An engine piston embodying two members fitting one within the other and each having a head, said members having a telescopic and slidable relation to each other, a. compression spring encircling one of the piston members and bearing at one end against the other piston member, and a spring holding collar surrounding the piston member which is encircled by saidcompression spring, said spring acting to yieldingly hold the heads of the piston members separated.

2. An engine piston embodying two members fitting one within the other and each having a head, said members having a telescopic and slidable relation to each other, a compression spring encircling one of the piston members and. bearing at one end against the other piston member, a spring holding collar surrounding the piston member which is encircled by said compression spring, said spring acting to yieldingly hold the heads of the piston'members separated,

. and means for limiting the separating movement of said heads.

3. An engine piston embodying two memlthe head of the inner piston member being vented.

4. An engine piston embodying two mem'- bers fitting one within the other and each having a head, said members having a telescopic and slidable relation to each other, a compression spring encircling one of the piston members and bearing at one end against the other piston member, and a spring holding collar surrounding the piston member which is encircled by said compression spring, said spring acting to yieldingly hold the heads of the piston members separated, said collar being removable from and adjustable on the pistonmember `which itk surrounds for increasing or diminishing the tension of said spring.

5. An engine piston embodying two members fitting one within the other and each having a head, said members having a telescopic and slidable relation to each other, a

compression spring encircling one of the piston members andvbearing at one Aend against the other piston member, and a spring holding collar surrounding the piston member which 4is encirgled by said compression spring, said spring acting to yieldingly hold the heads of the piston members separated, said spring having an expansive strength slightly less than the normal compression of the cylinder in which the piston operates. y

lIn testimony whereof we afliX our signatures.

CHARLES D. JOHNSON. PETER (l. JOHNSON. 

